"""Compare two directories of same-sized PNG frames."""

import argparse
from pathlib import Path

import numpy as np
from PIL import Image


parser = argparse.ArgumentParser()
parser.add_argument("a", type=Path)
parser.add_argument("b", type=Path)
parser.add_argument("--frames", type=int, required=True)
args = parser.parse_args()

rows = []
for index in range(args.frames):
    a = np.asarray(Image.open(args.a / f"frame_{index:04d}.png")).astype(np.int16)
    b = np.asarray(Image.open(args.b / f"frame_{index:04d}.png")).astype(np.int16)
    diff = np.abs(a - b)
    rows.append((index, int(diff.max()), float(diff.mean()), float(np.percentile(diff, 99))))

print({
    "frames": args.frames,
    "max": max(row[1] for row in rows),
    "mean": sum(row[2] for row in rows) / len(rows),
    "top_max": sorted(rows, key=lambda row: row[1], reverse=True)[:10],
    "top_mean": sorted(rows, key=lambda row: row[2], reverse=True)[:10],
})